Fish finders have evolved dramatically in recent years. We’re no longer bound to traditional sonar charts and flashers (though those tools are still indispensable). Devices have become more affordable and more powerful. CHIRP sonar, bigger screens—the list of evolutions goes on.
One of the biggest changes to fish finder technology is the ability to get clear images of structure below the water. Down imaging and side imaging are two such technologies. How do they work? What are the pros and cons of each?
That’s what you’re here to learn—and we’re happy to provide the answers. Keep reading for everything you need to know about down and side imaging!
Down imaging technology allows you to see what’s happening directly below your transducer. More specifically, it leverages the power of your transducer—and algorithms in your fish finder’s control head—to produce high-quality images of what’s beneath your boat.
The technology isn’t quite like a video camera—sonar doesn’t excel at showing things in real time. Instead, the most recent data appears on the right side of your screen—similar to traditional sonar. Stronger returns appear in lighter shades, while weaker returns appear in darker shades.
You’ll see a variety of different names for down imaging technology. The three most popular are:
We have to say, Humminbird won the naming game here—almost all anglers refer to the ability to get images below your boat using sonar as “down imaging”, regardless of brand.
With down imaging, you’ll be able to see bottom structure in unprecedented clarity. We’ll go deeper into how you can use down imaging to improve your angling in a bit—for now, we just wanted to briefly introduce the technology.
That brings us to the next piece of tech you want to know about:
Side imaging is almost exactly like down imaging, but instead of offering you images of what’s happening below the transducer, it shows what you can see to the left and right of the transducer.
Another way of explaining it is that side imaging offers a horizontal view, while down imaging offers a vertical perspective.
You might be wondering how to read side imaging sonar—if you’re seeing the right and left sides of your boat, the history of your sonar returns can’t move from right to left. The answer is simple—the most recent returns appear at the top of your screen, then move toward the bottom.
Getting the hang of reading side imaging is pretty simple. The strength of returns is the same as with side imaging—stronger returns lead to darker colors. Once you use side imaging, you’ll see that it’s pretty intuitive—you can quite literally see structure, fish, vegetation, and more. Explaining it is actually more complicated than just looking at it.
As with down imaging, you’ll find that different brands have different names for their side imaging technology. The three most common are:
Side imaging technology is a real boon for anglers. Now that you understand what both side and down imaging technology do, it’s time to look at the pros and cons of each.
To understand the pros of down imaging, we’ve got to ask an important question:
What are you using down imaging for?
The technology underpinning down imaging is pretty incredible. You’ll be able to see bottom structure, vegetation, and even fish. Baitfish, schools of fish, even the fish that you want to catch. That means you can use down imaging in all kinds of different scenarios. Our two favorites are:
Want to fish off a drop? Down imaging will help you find those drops. Want to fish around interesting structures like sunken boats? Down imaging will help you there, too. A great down-imaging fish finder will also offer you clearer images of fish than traditional 2D sonar. Your traditional sonar chart might show one or two fish—but if you look at your down imaging screen, it might reveal that there are actually quite a few fish that the traditional chart didn’t pick up.
Down imaging is also an excellent choice if you’re not used to reading 2D charts. By switching between your down imaging chart and your 2D chart, you’ll be able to learn how baitfish, schools of fish, and larger fish look on 2D charts. That’s because you’ll get a clear image of the fish on your down imaging chart—it’s great for learning what different arcs mean on your traditional view.
The disadvantages of down imaging are threefold: First, fish finders with down imaging are more expensive than those without. Second, you need to be in motion for your down imaging features to work—if you stay still, you’ll get inaccurate readings. Third, you might find yourself relying too much on down imaging—even in circumstances where you’d be better served by traditional charts.
In summary:
Pros:
Cons:
Let’s move on to the pros and cons of side imaging:
Many of the advantages of down imaging apply to side imaging. The technology is great for pre-fishing lakes and for finding the perfect spot to set up shop and start fishing.
The biggest advantage of side imaging, though, is that it lets you see things that wouldn’t be visible through down imaging or 2D sonar.
Side imaging extends hundreds of feet out to the sides of your vessel. You’ll be able to see structure, fish, vegetation, and other features that would normally only be visible if you passed directly over them. This makes side imaging the perfect tool for scouting out great fishing spots. You’re effectively multiplying the range of your sonar by several times.
This makes side imaging an incredible tool for scouting. Love trolling for fish? Side imaging is perfect for that, too. You need to be in motion to use side imaging properly—and you need to be in motion to troll. Casting far off the side of your boat is a common trolling tactic, making side imaging a perfect complement.
The main disadvantage of side imaging is that you can’t use it to see below your boat. For that, you’ll need to continue to rely on traditional sonar or down imaging. Additionally, your boat will need to be in motion to use side imaging. To no one’s surprise, side imaging is also more expensive than traditional sonar—it’s also more expensive than down imaging (more on that in the next section).
In summary:
Pros:
Cons:
Ahhh, a trick question! You probably didn’t know this was a trick question, but it is.
When price isn’t an issue, a device with side imaging is strictly better than one with only down imaging.
That’s because all devices with side imaging have down imaging, too!
Seriously. We’ve scanned the market up, down, and to the side, and we haven’t seen a single side imaging device that doesn’t also offer down imaging. In other words, if you think you have to choose between down imaging and side imaging, you don’t—by getting side imaging, you’ll get down imaging, too.
That being said, a device with side imaging is more expensive than one with down imaging alone. In our fishing adventures, we’ve tended to find down imaging more useful than side imaging, so if you absolutely cannot afford side imaging, don’t worry. The difference between down imaging and traditional sonar alone, however, is night and day—we highly recommend getting at least a down imaging device on your vessel.
Side imaging is your best bet for trolling. Side imaging works wonders when you’re moving at a slow, steady pace. Additionally, trolling often involves casting several lines—some of them quite far out—and casting from both sides of your vessel. Side imaging fits the bill perfectly.
That’s up to you! Depending on how you fish, you might benefit a lot from side imaging, and almost all kayakers can benefit from down imaging. While we can’t give a clear answer (as it’s so dependent on your fishing style and the body of water you fish in), we can say you’ll want a relatively small device.
Absolutely. Finding structure is one of the main benefits of both side imaging and down imaging sonar.
